Pollutants reduced by 18% on odd-even days, US-based study

New Delhi: The volume of respirable pollutants in the city's air reduced by 18 per cent during the odd-even scheme that regulated the plying of four-wheelers on Delhi roads for a fortnight, a new study has claimed.

While absolute pollution levels increased across the National Capital Region (NCR) in January as compared to the previous month, the levels in Delhi saw a "smaller increase" owing to the pilot license plate policy, the US-based study stated.

Jointly conducted by researchers at the Energy Policy Institute at the University of Chicago (EPIC) and Evidence for Policy Design group at Harvard University, the study found "stark reductions" in pollutants around the noon hours from January 1 to 15.

The impact was much "higher" during the hours when the scheme was in force as the gap between Delhi's pollution and the neighbouring regions widened steadily until at least midnight, the study said.

The study has based its findings on Central Pollution Control Board and private portal IndiaSpend data.

"Particulates (PM 2.5) declined by 10-13 per cent on an average (i.e overall 24 hours) and by 18 per cent on average during the period when the scheme was in force (i.e between 8 AM to 8 PM).

"After 8 PM there was (as expected) no effect, which is why the average for overall 24 hours is lower than the average of daytime," Anant Sudarshan, Director EPIC-India, told PTI.

PM 2.5, the tiniest and deadliest of all respirable pollutants, measures around 2.5 microns enabling it to embed deep into the lungs and subsequently enter the bloodstream.

Its safe limit is 60 ug/m3 as per Indian standards.

The conclusion was arrived at by comparing Delhi's pollution figures to that of Faridabad, Gurgaon and Noida, where the scheme was not enforced, as the NCR region has very similar weather conditions and are "equally exposed" to external factors affecting such as crop burning in the nearby states.

Under the scheme, cars with odd and even number registration plates plied on alternate days for the first 15 days of the year. Delhi Government is likely to roll out its second phase in March-April, after the completion of the board exams.